Estimated average glucose (eAG) translates an A1c percentage into the average blood glucose level, in mg/dL or mmol/L, that it corresponds to over roughly the prior two to three months, using the ADAG Study Group's regression formula.

How is eAG calculated from A1c?

eAG (mg/dL) = 28.7 x A1c(%) - 46.7. This regression was published by the A1c-Derived Average Glucose (ADAG) Study Group (Nathan et al., Diabetes Care, 2008) and is the formula the American Diabetes Association uses for its own eAG conversion tool.

Should I use mg/dL or mmol/L?

mg/dL is the standard unit in the United States. mmol/L is the SI unit used in most other countries, including Canada, the UK, and Australia. Use whichever unit matches your glucose meter, lab report, or continuous glucose monitor.

Can eAG replace glucose monitoring?

No. eAG is an optional cross-reference derived from a single A1c value. It does not replace daily glucose testing or continuous glucose monitoring, which capture real-time fluctuations that a single A1c-derived estimate cannot.

Why might my glucose meter average differ from my calculated eAG?

A1c reflects glucose bound to hemoglobin over the roughly 90-120 day lifespan of red blood cells, weighted toward more recent weeks. A meter or CGM average over a shorter window, or conditions affecting red blood cell turnover (anemia, hemoglobin variants, recent transfusion), can shift eAG away from your directly measured average.

Estimated Average Glucose (eAG) Calculator — A1c to Glucose

Q: How accurate is the eAG conversion?

The ADAG formula is a population regression derived from roughly 500 adults, so it approximates the relationship well on average but an individual's true glucose average can differ from the calculated eAG by 15-20 mg/dL or more.

A1c (%)	eAG (mg/dL)	eAG (mmol/L)
5.0	97	5.4
6.0	126	7.0
7.0	154	8.6
8.0	183	10.2
9.0	212	11.7
10.0	240	13.3
11.0	269	14.9
12.0	298	16.5

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Walk-through

How to Use This Calculator

3 steps

1

Pick a Direction

Choose A1c to eAG if you have a lab HbA1c result and want the average glucose it corresponds to, or eAG to A1c if you have a glucose meter or CGM average and want an estimated A1c.

2

Enter Your Value and Unit

Type your A1c percentage or glucose value, and select mg/dL or mmol/L depending on which unit your lab report, meter, or continuous glucose monitor uses.

3

Read Your Result

The hero number updates instantly and the sentence below it spells out the conversion in plain language. Check the reference table for the standard ADAG values at common A1c levels.

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Reference

Formula & Methodology

3 formulas

eAG from A1c (ADAG regression)

eAG (mg/dL) = 28.7 x A1c(%) - 46.7

The ADAG Study Group's published regression relating A1c percentage to estimated average glucose in mg/dL (Nathan et al., Diabetes Care, 2008).

A1c from eAG (inverse)

A1c(%) = (eAG(mg/dL) + 46.7) / 28.7

The algebraic rearrangement of the same ADAG regression, used when you start from a glucose value and want an estimated A1c.

mg/dL to mmol/L

mmol/L = mg/dL / 18.016

Standard glucose unit conversion using the precise molar-mass-derived factor (180.16 g/mol / 10), applied consistently to both the input and the result.

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High YMYL

Trust, Methodology & Sources

Reviewed by Calculover Editorial Review · Updated 2026-07-23 · 2 sources

Editorial accountability

Author: Quinn Sumner - Editor

Owner: Quinn Sumner - Editorial owner

Reviewer: Calculover Editorial Review - Medical-source review

Last reviewed: 2026-07-23

Last verified: 2026-07-23

Data effective: 2026-07-23

Methodology

This calculator applies the ADAG Study Group's published regression directly to the user's entered A1c or glucose value, in either direction, with no adjustment for individual red blood cell turnover or other physiological factors.

Assumption: The A1c value came from a standard lab HbA1c test, or the glucose value came from a meter or continuous glucose monitor average.

Assumption: eAG is a population-derived regression, not a personalized measurement of the user's actual average glucose.

Assumption: Red blood cell turnover is typical unless a clinician has indicated otherwise.

Limitations & guidance

This calculator performs a mathematical conversion only — it does not diagnose, manage, or monitor diabetes.

An individual's true glucose average can differ from the calculated eAG by 15-20 mg/dL or more, especially with anemia, hemoglobin variants, recent blood transfusion, or atypical red blood cell turnover.

Do not adjust medication or insulin dosing based on this calculator alone.

Professional guidance: This calculator is for health education and calculation transparency only. It is not medical advice, diagnosis, treatment, medication guidance, or a substitute for care from a licensed healthcare professional.

Primary sources

Nathan DM, et al; A1c-Derived Average Glucose (ADAG) Study Group. Translating the A1C Assay Into Estimated Average Glucose Values. - Diabetes Care. 2008;31(8):1473-1478.

A1C Test for Diabetes and Prediabetes - Centers for Disease Control and Prevention

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Glossary

Key Terms Explained

6 terms

eAG Estimated Average Glucose — the average blood glucose level, in mg/dL or mmol/L, that a given A1c percentage corresponds to according to the ADAG regression.

A1c (HbA1c) Glycated hemoglobin — a lab test measuring the percentage of hemoglobin with glucose attached, reflecting average blood sugar over roughly two to three months.

ADAG Study The A1c-Derived Average Glucose study (Nathan et al., 2008) that established the linear relationship this calculator uses between A1c and average glucose.

mg/dL Milligrams per deciliter — the standard blood glucose unit used in the United States and a handful of other countries.

mmol/L Millimoles per liter — the SI blood glucose unit used internationally, including in Canada, the UK, and Australia.

Population regression A statistical average derived from a study group rather than a direct personal measurement — meaning an individual's true glucose average can differ from the calculated eAG.

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Scenarios

Real-World Examples

3 worked examples

RK

Priya, 39 — Reading a Lab A1c Result

A1c to eAG

Direction A1c → eAG A1c 7.0% Unit mg/dL

Priya's lab report shows an A1c of 7.0%. Entering it here converts to an eAG of about 154 mg/dL (8.6 mmol/L) — a concrete glucose number she can compare against her meter readings and discuss with her provider.

DL

Marcus, 55 — Working Backward from a Meter Average

eAG to A1c

Direction eAG → A1c eAG 150 mg/dL Unit mg/dL

Marcus's glucose meter has been averaging 150 mg/dL over the past few weeks. Running that value backward through the ADAG formula gives an estimated A1c of about 6.9% — useful context before his next lab draw, though only a lab test gives the actual result.

EN

Elena, 47 — Using International Units

mmol/L conversion

Direction A1c → eAG A1c 6.5% Unit mmol/L

Elena's clinic in Toronto reports glucose in mmol/L. Selecting that unit converts her 6.5% A1c to an eAG of about 7.8 mmol/L (140 mg/dL) — the same underlying regression, just displayed in the unit her lab uses.

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Deep Dive

Understanding Estimated Average Glucose (eAG)

3 chapters · 4 min read

This calculator does one thing: it converts between an A1c percentage and the estimated average glucose (eAG) it corresponds to, in either direction, using the ADA-endorsed ADAG regression. It is meant as a quick, focused cross-reference — not a full diabetes management tool.

What eAG Means

A1c results are reported as a percentage, which is useful for tracking trends but does not map intuitively onto the mg/dL or mmol/L numbers most people see on a glucose meter or continuous glucose monitor day to day. Estimated average glucose (eAG) closes that gap by translating an A1c percentage into the average blood glucose value it statistically corresponds to over roughly the same two-to-three-month window the A1c test itself reflects.

The American Diabetes Association reports eAG alongside A1c on its own patient materials specifically so that people can relate a lab percentage to the glucose units they already track daily. This calculator applies the identical published formula, so the number you get here will match what a clinic or ADA calculator would report for the same input.

Where the Formula Comes From

The eAG regression comes from the A1c-Derived Average Glucose (ADAG) study, published by Nathan and colleagues in Diabetes Care in 2008. Researchers had roughly 500 adults wear continuous glucose monitors and take frequent self-measured glucose readings over several months, then compared those measured averages against each participant's lab A1c. The result was a simple linear relationship: eAG (mg/dL) = 28.7 x A1c(%) - 46.7.

Because the formula is a straight-line fit to real average-glucose data rather than a theoretical derivation, it is described as a population regression. That is a meaningful distinction from a calculation like an exact unit conversion — the formula estimates the typical relationship for people similar to the study cohort, not a physical law that holds identically for every individual.

Why Your Personal Average Can Differ

Because eAG is derived from a study average rather than measured directly, an individual's true glucose average can differ from the calculated eAG by a meaningful margin — commonly cited as 15 to 20 mg/dL in either direction. Differences in red blood cell lifespan (affected by iron-deficiency anemia, hemolytic conditions, recent blood transfusion, or hemoglobin variants) can shift a person's A1c away from what their actual glucose average would predict, which in turn shifts the eAG calculated from it.

For this reason, eAG works best as a translation aid — a way to sanity-check a lab A1c against the glucose numbers you already see on a meter or CGM — rather than as a substitute for either measurement. If your calculated eAG consistently diverges from your directly measured average, that is worth raising with a clinician rather than adjusting anything based on this calculator alone.

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Questions

Frequently Asked Questions

6 questions

What does this calculator actually compute?+

It converts between an A1c percentage and the estimated average glucose (eAG) that corresponds to it, in either direction, using the ADAG Study Group's published regression: eAG (mg/dL) = 28.7 x A1c(%) - 46.7.

How accurate is the eAG conversion?+

The formula is a population regression built from roughly 500 study participants, so it captures the typical relationship well on average, but an individual's true glucose average can differ from the calculated eAG by 15-20 mg/dL or more.

Should I enter mg/dL or mmol/L?+

Use whichever unit matches your lab report, glucose meter, or continuous glucose monitor. mg/dL is standard in the United States; mmol/L is the SI unit used internationally, including Canada, the UK, and Australia.

Can I convert from a glucose reading back to an estimated A1c?+

Yes. Switch the direction selector to eAG to A1c, enter your average glucose value and its unit, and the calculator applies the algebraic inverse of the same ADAG formula to estimate the corresponding A1c.

Can eAG replace regular glucose monitoring or an A1c test?+

No. eAG is an optional cross-reference calculated from a single A1c value or glucose average. It does not replace daily glucose testing, continuous glucose monitoring, or a lab A1c test, and it should not be used to adjust medication or insulin dosing on its own.

Why might my glucose meter average differ from the eAG calculated here?+

A1c reflects glucose bound to hemoglobin over the roughly 90-120 day lifespan of red blood cells, weighted toward more recent weeks, while a meter or CGM average covers whatever window you select. Conditions affecting red blood cell turnover, such as anemia, hemoglobin variants, or a recent transfusion, can also widen the gap between the two numbers.

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Estimated Average Glucose Calculator

Conversion

Result

Standard A1c-to-eAG Table

How to Use This Calculator

Pick a Direction

Enter Your Value and Unit

Read Your Result

Formula & Methodology

Trust, Methodology & Sources

Key Terms Explained

Real-World Examples

Priya, 39 — Reading a Lab A1c Result

Marcus, 55 — Working Backward from a Meter Average

Elena, 47 — Using International Units

Understanding Estimated Average Glucose (eAG)

What eAG Means

Where the Formula Comes From

Why Your Personal Average Can Differ

Frequently Asked Questions

Get a branded PDF of your results

Estimated Average Glucose Calculator

Conversion

Result

Standard A1c-to-eAG Table

How to Use This Calculator

Pick a Direction

Enter Your Value and Unit

Read Your Result

Formula & Methodology

Trust, Methodology & Sources

Key Terms Explained

Real-World Examples

Understanding Estimated Average Glucose (eAG)

What eAG Means

Where the Formula Comes From

Why Your Personal Average Can Differ

Frequently Asked Questions

Get a branded PDF of your results

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